Well, that system won't have a problem
UT2003 is a game that "feels" very different to UT. It takes longer to learn and require you to think a little differently about how you fight. At first there can be a big "what the
hell is going on?!" thing, but don't worry about it, stick with it, and you'll get the idea. Take some time to get used to double-jumping and dodge-jumping, they'll make you much harder to hit and will make you a lot faster around the maps (don't worry about the more advanced stuff, you won't need it yet). There are loads of short-cuts in the maps that can be used with just the double-jump and dodge-jump, the key as always is to know the map inside-out
One thing you'll notice in UT2003 is that the weapon switch is a lot faster. This means you won't be able to stick with one weapon a lot like in UT, you need to get used to switching to the right weapon for the right situation (a skill I still havn't mastered quite yet
). Just about the only weapon in UT2003 that isn't that useful is the link gun, everything else can be lethal in the right situation. The lightning gun is an awesome weapon at long/mid range, as it the shock rfile. At ultra close range the flak and the bio rifle are highly effective (the bio rifle is a LOT more powerful compared to UT). The flak secondary is very powerful (and great for short range covering fire in team games). Mid range the rocket launcher is still a very versatile weapon, and the minigun is useful for mopping up (but it's less effective than the UT minigun). The shock combo is a little different and uses more ammo.
Adrenaline is a big new feature in UT2003, but it can unbalance games, so a lot of servers have it switch off or limited. Once you get 100 adrenaline (the adrenaline total is in the top right hand of your hud), you can activate one of four combos:
Berzerk: forward, forward, back, back (increase weapon rate of fire, not very useful)
Booster: back, back, back, back (health and armour regeneration, extrememly useful)
Invisibility: left, left, right, right (pretty self-explanatory, can be pretty useful in DM and can cause chaos in team games)
Speed: forward, forward, forward, forward (significant increase in run speed and jump distance, useless in DM, but can massivly unbalance team games)
Once a combo is activated, your adrenaline will drain to zero (and will go to zero instantly if you die while a combo is activated, the worst thing in the world is to be killed
just as you activate a combo). Invisibility, Speed and Berzerk will last for a short time and then run out. However, Booster is the only combo that's effects last. If Booster regens your health armour to full, it'll stay full once the combo has worn off, so you don't loose the extra health/armour when the combo runs out (although the regen effect itself won't last). I normally trigger Booster, unless theres a specific reason not to. If I'm trying to return my team's flag in CTF, using Invisibility is a great way to get to the flag carrier without getting spotting